There is an unmet need to develop novel chemotherapeutics that enhance selectivity and specificity for targeting chemo-resistant tumors. In particular, new strategies that attack chemotherapy-insensitive cancer stem cells/tumor initiating cells (TICs) are lacking. The goal of this proposal is to understand the interplay between TICs and their microenvironment during the transition to invasion and metastasis, as well as to develop a novel treatment reagent to specifically induce invasive TIC death in a preclinical setting. Our central hypothesis is that a cell surface-anchored protease, matrix metalloproteinase-14 (MMP-14), is a key molecule capable of executing the switch in epithelial TICs from quiescent to invasive cells, thereby controlling metastasis. Development of reagents to selectively and specifically target invasive TICs utilizing an MMP-14 binding peptide will facilitate prevention of cancer dissemination. The rationale for this project is that the development of a specific tumor-homing vehicle that carries inhibitory peptide and cytotoxic drug will allow us to not only block cancer invasion but to also induce cancer cell death. Furthermore, this study will advance our understanding of how the microenvironment influences quiescent TICs to give rise to metastases. We plan to test our hypothesis by pursuing the following three specific aims:1) Elucidate the role and mechanism of MMP-14 in conversion of quiescent TICs to invasive cells under hypoxic conditions; 2) Define the mechanism of action of an MMP-14 homing peptide; and 3) Develop a bi-functional reagent that specifically targets cancer invasiveness and induces cancer cell death. With respect to the expected outcomes, the work proposed in this application will potentially result in development of a bi-functional reagent capable of delivering a potent chemotherapeutic drug to invasive TICs. This project is innovative because it utilizes novel peptides specific for MMP-14 to selectively target invasive TICs. The proposed research will have significant future implications because it is expected to vertically advance our understanding of how quiescent TICs become reprogrammed into invasive TICs in a hypoxic environment. The developed bi-functional reagent will have a positive impact on future cancer prevention/treatment and could eventually improve the outcome of patients with cancer.